Template(3)

NAME
Template - Front-end module to the Template Toolkit

SYNOPSIS
  use Template;

  # some useful options (see below for full list)
  my $config = {
      INCLUDE_PATH => '/search/path',  # or list ref
      INTERPOLATE  => 1,               # expand "$var" in plain text
      POST_CHOMP   => 1,               # cleanup whitespace
      PRE_PROCESS  => 'header',        # prefix each template
      EVAL_PERL    => 1,               # evaluate Perl code blocks
  };

  # create Template object
  my $template = Template->new($config);

  # define template variables for replacement
  my $vars = {
      var1  => $value,
      var2  => \%hash,
      var3  => \@list,
      var4  => \&code,
      var5  => $object,
  };

  # specify input filename, or file handle, text reference, etc.
  my $input = 'myfile.html';

  # process input template, substituting variables
  $template->process($input, $vars)
      || die $template->error();

DESCRIPTION
This documentation describes the Template module which is the direct Perl interface into the Template Toolkit. It covers the use of the module and gives a brief summary of configuration options and template directives. Please see Template::Manual for the complete reference manual which goes into much greater depth about the features and use of the Template Toolkit. The Template::Tutorial is also available as an introductory guide to using the Template Toolkit.

METHODS

  new(\%config)
The new() constructor method (implemented by the Template::Base base class) instantiates a new Template object. A reference to a hash array of configuration items may be passed as a parameter.

    my $tt = Template->new({
        INCLUDE_PATH => '/usr/local/templates',
            EVAL_PERL    => 1,
    }) || die $Template::ERROR, "\n";

A reference to a new Template object is returned, or undef on error. In the latter case, the error message can be retrieved by calling error() as a class method (e.g. "Template->error()") or by examining the $ERROR package variable directly (e.g. $Template::ERROR).

    my $tt = Template->new(\%config)
        || die Template->error(), "\n";

    my $tt = Template->new(\%config)
        || die $Template::ERROR, "\n";

For convenience, configuration items may also be specified as a list of items instead of a hash array reference. These are automatically folded into a hash array by the constructor.

    my $tt = Template->new(INCLUDE_PATH => '/tmp', POST_CHOMP => 1)
        || die $Template::ERROR, "\n";

  process($template, \%vars, $output, %options)
The process() method is called to process a template. The first parameter indicates the input template as one of: a filename relative to INCLUDE_PATH, if defined; a reference to a text string containing the template text; or a file handle reference (e.g. IO::Handle or sub-class) or GLOB (e.g. \*STDIN), from which the template can be read. A reference to a hash array may be passed as the second parameter, containing definitions of template variables.

    $text = "[% INCLUDE header %]\nHello world!\n[% INCLUDE footer %]";

    # filename
    $tt->process('welcome.tt2')
        || die $tt->error(), "\n";

    # text reference
    $tt->process(\$text)
        || die $tt->error(), "\n";

    # GLOB
    $tt->process(\*DATA)
        || die $tt->error(), "\n";

    __END__
    [% INCLUDE header %]
    This is a template defined in the __END__ section which is
    accessible via the DATA "file handle".
    [% INCLUDE footer %]

By default, the processed template output is printed to STDOUT. The process() method then returns 1 to indicate success. A third parameter may be passed to the process() method to specify a different output location. This value may be one of: a plain string indicating a filename which will be opened (relative to OUTPUT_PATH, if defined) and the output written to; a file GLOB opened ready for output; a reference to a scalar (e.g. a text string) to which output/error is appended; a reference to a subroutine which is called, passing the output as a parameter; or any object reference which implements a 'print' method (e.g. IO::Handle, Apache::Request, etc.) which will be called, passing the generated output as a parameter.

Examples:

    # output filename
    $tt->process('welcome.tt2', $vars, 'welcome.html')
        || die $tt->error(), "\n";

    # reference to output subroutine
    sub myout {
        my $output = shift;
            ...
    }
    $tt->process('welcome.tt2', $vars, \&myout)
        || die $tt->error(), "\n";

    # reference to output text string
    my $output = '';
    $tt->process('welcome.tt2', $vars, \$output)
        || die $tt->error(), "\n";

    print "output: $output\n";

In an Apache/mod_perl handler:

    sub handler {
        my $req = shift;

        ...

        # direct output to Apache::Request via $req->print($output)
        $tt->process($file, $vars, $req) || do {
            $req->log_reason($tt->error());
            return SERVER_ERROR;
        };

        return OK;
    }

After the optional third output argument can come an optional reference to a hash or a list of (name, value) pairs providing further options for the output. The only option currently supported is "binmode" which, when set to any true value will ensure that files created (but not any existing file handles passed) will be set to binary mode.

    # either: hash reference of options
    $tt->process($infile, $vars, $outfile, { binmode => 1 })
        || die $tt->error(), "\n";

    # or: list of name, value pairs
    $tt->process($infile, $vars, $outfile, binmode => 1)
        || die $tt->error(), "\n";

Alternately, the binmode argument can specify a particular IO layer such as ":utf8".

    $tt->process($infile, $vars, $outfile, binmode => ':utf8')
        || die $tt->error(), "\n";

The OUTPUT configuration item can be used to specify a default output location other than \*STDOUT. The OUTPUT_PATH specifies a directory which should be prefixed to all output locations specified as filenames.

    my $tt = Template->new({
        OUTPUT      => sub { ... },       # default
            OUTPUT_PATH => '/tmp',
        ...
    }) || die Template->error(), "\n";

    # use default OUTPUT (sub is called)
    $tt->process('welcome.tt2', $vars)
        || die $tt->error(), "\n";

    # write file to '/tmp/welcome.html'
    $tt->process('welcome.tt2', $vars, 'welcome.html')
        || die $tt->error(), "\n";

The process() method returns 1 on success or undef on error. The error message generated in the latter case can be retrieved by calling the error() method. See also "CONFIGURATION SUMMARY" which describes how error handling may be further customised.

  error()
When called as a class method, it returns the value of the $ERROR package variable. Thus, the following are equivalent.

    my $tt = Template->new()
        || die Template->error(), "\n";

    my $tt = Template->new()
        || die $Template::ERROR, "\n";

When called as an object method, it returns the value of the internal _ERROR variable, as set by an error condition in a previous call to process().

    $tt->process('welcome.tt2')
        || die $tt->error(), "\n";

Errors are represented in the Template Toolkit by objects of the Template::Exception class. If the process() method returns a false value then the error() method can be called to return an object of this class. The type() and info() methods can called on the object to retrieve the error type and information string, respectively. The as_string() method can be called to return a string of the form "$type - $info". This method is also overloaded onto the stringification operator allowing the object reference itself to be printed to return the formatted error string.

    $tt->process('somefile') || do {
        my $error = $tt->error();
            print "error type: ", $error->type(), "\n";
        print "error info: ", $error->info(), "\n";
            print $error, "\n";
    };

  service()
The Template module delegates most of the effort of processing templates to an underlying Template::Service object. This method returns a reference to that object.

  context()
The Template::Service module uses a core Template::Context object for runtime processing of templates. This method returns a reference to that object and is equivalent to $template->service->context();

CONFIGURATION SUMMARY
The following list gives a short summary of each Template Toolkit configuration option. See Template::Manual::Config for full details.

  Template Style and Parsing Options

START_TAG, END_TAG
    Define tokens that indicate start and end of directives (default: '[%' and '%]').

TAG_STYLE
    Set START_TAG and END_TAG according to a pre-defined style (default: 'template', as above).

PRE_CHOMP, POST_CHOMP
    Remove whitespace before/after directives (default: 0/0).

TRIM
    Remove leading and trailing whitespace from template output (default: 0).

INTERPOLATE
    Interpolate variables embedded like $this or ${this} (default: 0).

ANYCASE
    Allow directive keywords in lower case (default: 0 - UPPER only).

  Template Files and Blocks

INCLUDE_PATH
    One or more directories to search for templates.

DELIMITER
    Delimiter for separating paths in INCLUDE_PATH (default: ':').

ABSOLUTE
    Allow absolute file names, e.g. /foo/bar.html (default: 0).

RELATIVE
    Allow relative filenames, e.g. ../foo/bar.html (default: 0).

DEFAULT
    Default template to use when another not found.

BLOCKS
    Hash array pre-defining template blocks.

AUTO_RESET
    Enabled by default causing BLOCK definitions to be reset each time a template is processed. Disable to allow BLOCK definitions to persist.

RECURSION
    Flag to permit recursion into templates (default: 0).

  Template Variables

VARIABLES, PRE_DEFINE
    Hash array of variables and values to pre-define in the stash.

  Runtime Processing Options

EVAL_PERL
    Flag to indicate if PERL/RAWPERL blocks should be processed (default: 0).

PRE_PROCESS, POST_PROCESS
    Name of template(s) to process before/after main template.

PROCESS
    Name of template(s) to process instead of main template.

ERROR
    Name of error template or reference to hash array mapping error types to templates.

OUTPUT
    Default output location or handler.

OUTPUT_PATH
    Directory into which output files can be written.

DEBUG
    Enable debugging messages.

  Caching and Compiling Options

CACHE_SIZE
    Maximum number of compiled templates to cache in memory (default: undef - cache all)

COMPILE_EXT
    Filename extension for compiled template files (default: undef - don't compile).

COMPILE_DIR
    Root of directory in which compiled template files should be written (default: undef - don't compile).

  Plugins and Filters

PLUGINS
    Reference to a hash array mapping plugin names to Perl packages.

PLUGIN_BASE
    One or more base classes under which plugins may be found.

LOAD_PERL
    Flag to indicate regular Perl modules should be loaded if a named plugin can't be found (default: 0).

FILTERS
    Hash array mapping filter names to filter subroutines or factories.

  Compatibility, Customisation and Extension

V1DOLLAR
    Backwards compatibility flag enabling version 1.* handling (i.e. ignore it) of leading '$' on variables (default: 0 - '$' indicates interpolation).

LOAD_TEMPLATES
    List of template providers.

LOAD_PLUGINS
    List of plugin providers.

LOAD_FILTERS
    List of filter providers.

TOLERANT
    Set providers to tolerate errors as declinations (default: 0).

SERVICE
    Reference to a custom service object (default: Template::Service).

CONTEXT
    Reference to a custom context object (default: Template::Context).

STASH
    Reference to a custom stash object (default: Template::Stash).

PARSER
    Reference to a custom parser object (default: Template::Parser).

GRAMMAR
    Reference to a custom grammar object (default: Template::Grammar).

DIRECTIVE SUMMARY
The following list gives a short summary of each Template Toolkit directive. See Template::Manual::Directives for full details.

GET Evaluate and print a variable or value.

        [%   GET variable %]    # 'GET' keyword is optional

        [%       variable %]
        [%       hash.key %]
        [%         list.n %]
        [%     code(args) %]
        [% obj.meth(args) %]
        [%  "value: $var" %]

CALL
    As per GET but without printing result (e.g. call code)

        [%  CALL variable %]

SET Assign a values to variables.

        [% SET variable = value %]    # 'SET' also optional

        [%     variable = other_variable
               variable = 'literal text @ $100'
               variable = "interpolated text: $var"
               list     = [ val, val, val, val, ... ]
               list     = [ val..val ]
               hash     = { var => val, var => val, ... }
        %]

DEFAULT
    Like SET above, but variables are only set if currently unset (i.e. have no true value).

        [% DEFAULT variable = value %]

INSERT
    Insert a file without any processing performed on the contents.

        [% INSERT legalese.txt %]

INCLUDE
    Process another template file or block and include the output. Variables are localised.

        [% INCLUDE template %]
        [% INCLUDE template  var = val, ... %]

PROCESS
    As INCLUDE above, but without localising variables.

        [% PROCESS template %]
        [% PROCESS template  var = val, ... %]

WRAPPER
    Process the enclosed block WRAPPER ... END block then INCLUDE the named template, passing the block output in the 'content' variable.

        [% WRAPPER template %]
           content...
        [% END %]

BLOCK
    Define a named template block for subsequent INCLUDE, PROCESS, etc.,

        [% BLOCK template %]
           content
        [% END %]

FOREACH
    Repeat the enclosed FOREACH ... END block for each value in the list.

        [% FOREACH variable = [ val, val, val ] %]    # either
        [% FOREACH variable = list %]                 # or
        [% FOREACH list %]                            # or
           content...
           [% variable %]
        [% END %]

WHILE
    Enclosed WHILE ... END block is processed while condition is true.

        [% WHILE condition %]
           content
        [% END %]

IF / UNLESS / ELSIF / ELSE
    Enclosed block is processed if the condition is true / false.

        [% IF condition %]
           content
        [% ELSIF condition %]
             content
        [% ELSE %]
             content
        [% END %]

        [% UNLESS condition %]
           content
        [% # ELSIF/ELSE as per IF, above %]
           content
        [% END %]

SWITCH / CASE
    Multi-way switch/case statement.

        [% SWITCH variable %]
        [% CASE val1 %]
           content
        [% CASE [ val2, val3 ] %]
           content
        [% CASE %]         # or [% CASE DEFAULT %]
           content
        [% END %]

MACRO
    Define a named macro.

        [% MACRO name <directive> %]
        [% MACRO name(arg1, arg2) <directive> %]
        ...
        [% name %]
        [% name(val1, val2) %]

FILTER
    Process enclosed FILTER ... END block then pipe through a filter.

        [% FILTER name %]                       # either
        [% FILTER name( params ) %]             # or
        [% FILTER alias = name( params ) %]     # or
           content
        [% END %]

USE Load a "plugin" module, or any regular Perl module if LOAD_PERL option is set.

        [% USE name %]                          # either
        [% USE name( params ) %]                # or
        [% USE var = name( params ) %]          # or
        ...
        [% name.method %]
        [% var.method %]

PERL / RAWPERL
    Evaluate enclosed blocks as Perl code (requires EVAL_PERL option to be set).

        [% PERL %]
             # perl code goes here
             $stash->set('foo', 10);
             print "set 'foo' to ", $stash->get('foo'), "\n";
             print $context->include('footer', { var => $val });
        [% END %]

        [% RAWPERL %]
           # raw perl code goes here, no magic but fast.
           $output .= 'some output';
        [% END %]

TRY / THROW / CATCH / FINAL
    Exception handling.

        [% TRY %]
             content
           [% THROW type info %]
        [% CATCH type %]
             catch content
           [% error.type %] [% error.info %]
        [% CATCH %] # or [% CATCH DEFAULT %]
             content
        [% FINAL %]
           this block is always processed
        [% END %]

NEXT
    Jump straight to the next item in a FOREACH/WHILE loop.

        [% NEXT %]

LAST
    Break out of FOREACH/WHILE loop.

        [% LAST %]

RETURN
    Stop processing current template and return to including templates.

        [% RETURN %]

STOP
    Stop processing all templates and return to caller.

        [% STOP %]

TAGS
    Define new tag style or characters (default: [% %]).

        [% TAGS html %]
        [% TAGS <!-- --> %]

COMMENTS
    Ignored and deleted.

        [% # this is a comment to the end of line
           foo = 'bar'
        %]

        [%# placing the '#' immediately inside the directive
            tag comments out the entire directive
        %]

AUTHOR
Andy Wardley <abw@wardley.org>

<http://wardley.org/|http://wardley.org/>

VERSION
Template Toolkit version 2.19, released on 27 April 2007.

COPYRIGHT
  Copyright (C) 1996-2007 Andy Wardley.  All Rights Reserved.

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.